How This Overlooked Battery Might Change Everything

Author: Matt Ferrell

Lithium-sulfur batteries were once kind of a joke. A chemistry so unstable and unreliable that no one took them seriously. But now? Multiple research teams have recently made strides in transforming sulfur from stinky stone to capable cathode. Some claim they’ve cracked the code — creating prototypes that charge faster than you can finish this video, and others that last 25,000 cycles. That’s basically a forever battery.

What changed? And could lithium-sulfur actually overthrow lithium-ion as the king of batteries?

Not too long ago, we talked about lithium-sulfur (Li-S) batteries and a breakthrough from Drexel University—monoclinic gamma-phase sulfur. No, not angry-green-monster sulfur, but a rare form that sidesteps the polysulfide problem — a flaw that has long kept Li-S batteries from reaching their full potential. And polysulfides? You’ll hear a lot about those today, so put a pin in that.

Since then, lithium-sulfur research has taken off. We’ll be getting into each of these in more detail:

• In Australia, the University of Adelaide developed an electrocatalyst that could slash charging times to just five minutes, a huge leap from the one to ten hours typical of Li-S batteries today.¹
• Over at Monash University, researchers took inspiration from an unexpected source — an antiseptic mainstay of surgical prep — to push lithium-sulfur closer to real-world EV use.²
• In South Korea, DGIST has also joined the race, unveiling a Li-S battery that charges in 12 minutes.³
• And to top it off, a recent Nature paper by an international team showcased an all-solid-state Li-S battery with an almost unbelievable 25,000-cycle lifespan that still holds 80% of its capacity.⁴

With game-changing potential for EVs, drones, and consumer electronics, lithium-sulfur could actually challenge lithium-ion’s dominance. But if Li-S is so promising, why hasn’t it taken over yet? To answer that, let’s dig into the technology itself.

Sulfur is dirt cheap, abundant, and safer than other cathode materials like cobalt and nickel, which already gives it a leg up. No nightmarish supply chain bottlenecks here. And while sulfur might smell like rotten eggs, the EPA assures us it poses “very little if any risk to human health.”⁵ It’s also more environmentally friendly than its competitors.⁶

But here’s where things get interesting: sulfur packs more energy per gram than cobalt, and it’s much lighter.⁶⁷ That’s a big deal for EVs and drones, where every ounce matters. In theory, Li-S batteries could store way more energy than lithium-ion. The problem? Reality hasn’t quite caught up to theory.

The Not-So-Great Lithium-Sulfur History

The idea of Li-S batteries dates back to 1962, when researchers patented the chemistry.⁸ But despite its promise, the formula had some serious issues that left it collecting dust for decades.⁹

The biggest problem? Polysulfide “shuttling.” I told you we’d get back to this. During discharge, the sulfur cathode creates polysulfides—pesky little molecules that dissolve into the electrolyte and slowly destroy the battery’s effectiveness.⁷ Worse, some of these polysulfides react with lithium to form a rock-hard crust (Li₂S) around the anode, blocking ion flow and killing the battery entirely.⁷

And the bad news doesn’t stop there:

• Slow charge and discharge rates meant Li-S batteries took forever to power up.¹
• Dendrites, or metal spikes that can form on lithium anodes, pose a risk of short circuits, impacting battery stability and safety.⁹
• Swelling issues — as sulfur absorbs lithium, it expands… sometimes so much that it literally bursts the casing.¹⁰¹¹

With all these problems, Li-S batteries were mostly just a lab curiosity…until 2009. That’s when a University of Waterloo team found a way to “cage” sulfur in a carbon framework, preventing swelling while improving stability.¹²

The Turning Point

Fast forward to 2020, and Monash University made a breakthrough: a special binding agent that gave sulfur extra elbow room, pushing Li-S batteries to 200 charge cycles.¹³ That might sound unimpressive, but for Li-S, it was a huge step.

Then, in 2021, Monash (literally) sweetened the deal by adding sugar. This blocked polysulfides from escaping, boosting the battery to 1,000 cycles with a respectable 700 mAh/g capacity.¹⁴⁹

And 2022? A banner year for Li-S research. Monash, the University of Michigan, and Drexel University all made breakthroughs using Kevlar fibers, gamma-phase sulfur, and other materials to extend battery life. Drexel even managed to quadruple Li-S cycle life to 4,000 cycles by accident.¹⁵¹⁶ I’ve got a whole video and interview on that.

So, with all these improvements, where does that leave lithium-sulfur today? Let’s dive into the latest breakthroughs.

New Li-Sulfur Breakthroughs

We’ve already talked about Monash University, but they’re not done yet. Their latest focus? Polysulfides, the ultimate battery buzzkill. This time, they took inspiration from an unlikely source: Betadine, the antiseptic.² Betadine contains polyvinylpyrrolidone. For my sake, let’s just call it PVP (now I’m thinking about playing Call of Duty). Anyway, in a Li-S battery, PVP acts as a catalyst, speeding up chemical reactions. Faster reactions mean faster charging and discharging.²¹⁷

And Monash isn’t thinking small. They claim their improvements could boost Li-S energy density to 400 Wh/kg, blowing past lithium-ion’s 150–235 Wh/kg.² That could mean EVs with a 600-mile range (1,000 km) and faster recharge times.¹⁸

Co-author of the paper Petar Jovanović described the potential of their breakthrough at: “this represents a major breakthrough toward making Li-S a feasible option not just for long-haul EVs but particularly in industries like aviation and maritime that require rapid, reliable power that is crucially light-weighted.” ¹⁸ Big if true, as they say.

The Need for Speed

Still in Australia, The University of Adelaide may have cracked the fastest-charging Li-S battery yet. Their secret? Fixing the sulfur reduction reaction (SRR): a necessary but painfully slow process that also happens to create polysulfides.¹⁹ Their solution? Nanotech, of course.

They landed on a cobalt-zinc (CoZn) nanocomposite electrocatalyst, which sounds like Star Trek technobabble, but basically, it supercharges sulfur reactions while keeping polysulfides in check. The result? A Li-S battery that lasts 1,000 cycles and can charge in just five minutes.¹²⁰²¹ Engage warp speed.

A Graphite Cage Match

Over in South Korea, the Daegu Gyeongbuk Institute of Science and Technology (DGIST) took another approach to tackling Li-S battery weaknesses: graphite scaffolding.³ Echoing that Waterloo breakthrough in 2009, DGIST is experimenting with scaffolding to keep those polysulfides contained.

Their researchers developed ZIF-8, a graphite-based, nitrogen-doped material. Again, sounds complex, but it’s actually simple. Let’s break down the two main components. Graphite is a very good conductor that shouldn’t surprise anyone. Nitrogen is the real secret sauce here. At high temperatures, the nitrogen reacts with the magnesium to form an especially strong and stable carbon structure that helps keep the sulfur from swelling. Meanwhile, the pore structure helps speed up sulfur loading, allowing the battery to charge super fast.²²

The result? A battery that charges in 12 minutes without turning into a molten deathtrap.³²² Even at rapid charging speeds, it holds 705 mAh/g⁻¹. DGIST claims this is a 1.6-fold improvement “over conventional batteries,” but this isn’t stated in the paper itself.³²³

The “Forever” Battery

And now for the showstopper: a Li-S battery that could last forever.

Okay, not literally forever, but how long is “forever”? A new study in Nature showcased an all-solid-state Li-S battery that can cycle 25,000 times while still retaining 80% capacity.⁴ The key here is solid electrolytes, which if you recall from many previous videos, tends to help promote battery safety and energy density. But solid-state Li-S batteries have a big weakness: the solid-solid sulfur redox reaction (SSSRR).

To speed things up, researchers added iodine to the mix.²⁴ This wasn’t an effort to treat a bad cut. Iodine can undergo reversible redox reactions, which lets the battery “skip the line” when transporting charge. The result? A Li-S battery with an insane lifespan: still going strong at room temperature after 25,000 cycles, and lasting 3,500 cycles even at 60°C.

And while this is very cool, and it feels like you’re gonna start seeing Li-S batteries on your store shelf any day now, I want to pull on the reins a little bit. These batteries aren’t without their flaws and there’s still some significant hurdles to overcome.

Remaining Drawbacks & Outlook

What are the hurdles keeping Li-S batteries from taking over? First off, they’re still stuck in the lab. The road from research paper to real-world product is long and bumpy, and many promising technologies never make it past this stage.

Even if one of these breakthroughs reaches commercialization, there’s another challenge: lithium-ion’s stranglehold on the market. Lithium-ion has been the dominant battery tech for decades, powering everything from phones to EVs to medical devices.²⁵ Even if Li-S batteries do prove superior, switching over won’t happen overnight. Infrastructure, supply chains, and manufacturing lines would all need major overhauls.

That said, there’s real momentum. Monash University told CleanTechnica they’re so confident in their Li-S tech that they plan to test it in commercial drones and eVTOL aircraft within a year.¹⁸ And with all the buzz around drones for both private and defense sectors, they’re bound to attract interest.

Speaking of commercialization, we have to mention Lyten. Last time we checked in, the California-based company was developing graphene-caged Li-S batteries to stop polysulfide issues. Their tests were promising enough that they started building a pilot plant capable of producing a quarter of a million cells per year.²⁶²⁷ They also claimed they converted the facility from lithium-ion to lithium-sulfur production in just six weeks for less than 2% of the total capital cost.²⁸ If true, that’s a huge point in favor of Li-S adoption.

But Lyten isn’t stopping there. They recently announced plans for a billion-dollar gigafactory in Reno, Nevada, set to produce up to 10 GWh of lithium-sulfur batteries annually.²⁸ Phase one is expected to go online by 2027, so we may not have to wait too long to see if they can deliver.

A lot of battery breakthroughs never make it out of the lab. But this time, things feel different. Li-S has gone from a scientific curiosity to something that actually has a path to commercialization. Will it replace lithium tomorrow, or even this year? No, but the potential is so great, they’re worth keeping up with.

So where does it land on the NASA Technology Readiness Scale? It’s complicated. The lab work from Monash, Adelaide, and DGIST is promising but still early-stage. Meanwhile, Lyten’s gigafactory plans push them much closer to commercialization. That puts things at maybe a TRL 8.²⁹

For now, we’ll have to wait and see if Li-S lives up to the hype.